Don't forget the DSI Modular Mac
, Cherry MX brown or blue in a compact tenkeyless. Razer do a Mac BlackWidow, but then you'd get blues.
If you want quiet, the Tactile Pro 3 is not for you, as simplified ALPS type II "Fukka" switches are particularly noisy and really kick up a din, much more so than blues. Buckling spring is even worse, but the retro typewriter clatter is a lot more satisfiying than cheap ALPS ping. Cherry MX brown and buckling spring are pretty much opposite ends of the keystroke force scale, and MX brown and Fukka ALPS pretty much opposite ends of the tactility scale – browns have a gentle background tactile feel, while ALPS can be best described as "jarring", as can Cherry MX blue. The only switch that has the smooth tactile feel of browns and BS but a nice medium weight is Topre (which I must confess I've really come to love now), but I've never seen a Mac Topre keyboard.
Fentek still have blank 1× keycaps
for IBM/Lexmark/Unicomp keyboards, but these are the upper half of two part keycaps, and Unicomp keyboards use one-part caps, so you need one two-part keycap stem
for each coloured key. Of course, this won't help you if you want coloured modifiers, but you could at least redo some of the 1× keys (maybe things like scroll lock, which is as useless in Windows as it would be on your Macintosh).
The best option of course is to buy an ADB to USB converter and snag an Apple Extended/Extended II – unlike the Tactile Pro 3, they're tactile not clicky and thus significantly quieter. (The Tactile Pro should be called the Clicky Pro, as it was Apple's keyboards that used the tactile switches.)